MNPV6-AC DISCO --- Nuisance Breaker Tripping

[harkrp]

Any ideas?

We installed two similar systems recently using the MNPV6-AC Disconnect switch to house the 2-pole breakers for the enphase branch circuits.  One install is on a residential roof, and the other is a ground mount. 

The roof install has had the breaker inexplicably trip one time in the past 4 months. 
The ground mount has 2 branches, and each branch has randomly tripped a few times in the past 4 months. 

All continuity checks out at both sites, and we can't find a cause of the trips.  Checked all connections to inverters as well as trunk cable terminations.  We removed the breaker grabber arm thinking that might not be allowing the breakers to fully sit in the on position.  All good...for a while.  Still getting trips at the ground mount.  The breakers are 20A 2PL but there are only 9 215w enphase micros on each branch, and the breakers have tripped even in the early morning hours....so it doesn't seem to be caused by overcurrent.  The two branch circuits at the ground mount have never tripped at the same time either.

It is strange that two jobs, same basic setup, and same problem.


Anyone had similar issue? Solution?
Faulty breakers?

I am afraid we may have to pull the boxes, install small load center with standard 2PL breakers, and an ac disconnect.  HUGE PAIN.

[Robin]

We have discovered that some micro inverters have such high output ripple current, they trip the 2 pole 20 amp breakers when only 16 amps are present. This tripping is a function of the hydraulic cylinder in the breaker being forced up the tube until it pops. Normal AC from the grid and from battery based inverters do not have this problem, but micro inverters are built cheap and that means very little output filtering. We have fixed this by going to a longer trip curve. Anyone that exhibits this problem should contact tech support so we can get new breakers out to you.